It is the purpose of this project to elucidate the mechanism of the immunologic rejection of tumor grafts and to determine the mechanism of tumor suppression following immunostimulation with BCG. Current and contemplated areas of investigation are: (1) induction of syngeneic tumors immunity in vitro; (2) analysis of the cell types involved in transfer of syngeneic tumor immunity in vitro; and (3) analysis of the mechanism of tumor cell destruction at the site of tumor rejection following injection of immunostimulants.